Magnetically-attractable non-clumping animal litter

ABSTRACT

A particulate non-clumping animal litter composition is disclosed. The composition comprises non-clumping absorbent particles bound to magnetically-attractable metal particles such that substantially all particles of the animal litter composition are attracted to a magnetic surface. The animal litter composition exhibits favorable properties such as absorbency, resiliency, homogeneity, and particle size. Methods of production for non-clumping animal litter compositions are also disclosed that employ sufficient shear to bind the non-clumping absorbent particulate material to the magnetically-attractable metal particles such that the animal litter compositions exhibit favorable properties. A method and apparatus for the collection of magnetically-attractable animal litter particles are also disclosed.

FIELD OF THE INVENTION

The present invention relates to a magnetically-attractable non-clumpingabsorbent animal dross composition and its method of manufacture anduse. More particularly, the present invention is directed to anabsorbent composition that is a combination of a non-clumping absorbentparticulate material and magnetically-attractable metal-containingparticles adhered together by high-shear mixing or extrusion to provideparticles having a favorable size distribution, while maintainingmagnetism in essentially every particle.

BACKGROUND AND PRIOR ART

U.S. Pat. No. 6,302,060 B1 ('060) describes a magnetic pet litterapparatus that includes a magnetically-attractable pet litter containedwithin a pet litter box, or other litter containment structure, andincludes one or more permanent magnets positioned externally to thelitter box to magnetically attract and collect particles of the litterbrought outside the litter box by a pet, such as a cat. As described inthe '060 patent, the pet litter is a mixture of a bentonite claycontaining sodium and 5% or more by weight of iron or a ferrous alloy.As described in the '060 patent, a preferred method of forming thelitter particles is to blend iron or iron oxide in slurry form with thebentonite clay, such as the bentonite clay described in this assignee'sU.S. Pat. No. 5,503,111.

As described in the '060 patent, pets such as cats that use litter boxestend to scatter particles of litter outside of the litter box leaving anunsanitary mess for the pet owner to clean. This typically happens when,upon exiting the litter box, the pet scatters litter with its feet. Themagnetically-attractable litter particles described herein arenon-clumping and are combined with a magnetically-attractable metal sothat the litter particles also are capable of being magnetically removedfrom a pet's feet upon exiting the litter box. Themagnetically-attractable non-clumping animal litter particles describedherein are particularly suitable for use in the magnetic apparatusdescribed in U.S. Pat. No. 6,302,060 B1, or any other magnetic litterapparatus capable of attracting magnetically-attractablemetal-containing litter particles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a magnetic sweeper inaccordance with the present disclosure.

FIG. 2 illustrates a perspective view of a hand-held electromagneticcollector in accordance with the present disclosure.

SUMMARY

Ranges may be expressed herein as from “about” or “approximately” oneparticular value and/or to “about” or “approximately” another particularvalue. When such a range is expressed, another embodiment includes fromthe one particular value and/or to the other particular value.Similarly, when values are expressed as approximations, by use of theantecedent “about,” it will be understood that the particular valueforms another embodiment.

In brief, the compositions described herein absorb animal dross whenwetted and are magnetically attracted to a confined magnetic area whenscattered from their intended location by a pet. Substantially all ofthe particles in the present composition are attracted to a static,horizontal magnetic surface. The composition comprises discreteparticles of a combined/adhered combination of amagnetically-attractable metal and non-clumping absorbent particulatematerial that effectively absorbs animal dross. The non-clumpingabsorbent particulate material is combined with magnetically-attractablemetal particles, preferably iron-containing particles, using ahigh-shear mixer, such as a pin mixer or extruder, to formmagnetically-attractable particles which maintain their absorbency,resiliency, homogeneity, and particle size. If extrusion is used,pellets are formed, and the pellets are divided into discrete,magnetically-attractable particles, e.g., in a suitable grinder or mill.

The process of manufacturing a non-clumping animal litter that ismagnetically-attractable is not a matter of simply combining anabsorbent material with iron or an iron alloy, as outlined in the '060patent, particularly from the standpoint of obtaining sufficientmagnetic attraction of essentially all of the particles and maintainingthe integrity of the litter particles. A non-clumping absorbentparticulate material and magnetically-attractable metal particles cannotsimply be slurried together to obtain a magnetically-attractable littercomposition, as described in the '060 patent.

In accordance with the method described herein, in order to providemagnetically-attractable non-clumping pet litter particles, it has beenfound that it is necessary to combine particles containing a metal thatis attracted to a magnet, such as iron, nickel or cobalt, of aparticular size distribution, together with a non-clumping absorbentparticulate material of a particular size distribution; provide each ina particular percentage by weight; mix the absorbent material andmetal-containing particles in a high-shear mixer; dry the particles toless than 15 weight % water (relative to the total weight of absorbentmaterial and water); and size the dried particles or pellets to aparticular size distribution. In one embodiment, a suitable binder iscombined with the absorbent material and metal-containing particles.

Therefore, one aspect of the compositions and methods described hereinis to provide an improved absorbent, magnetically-attractable littercomposition for animal waste products and related waste products.

Another aspect of the compositions and methods described herein is toprovide a magnetically-attractable litter composition that economicallyeliminates or reduces odors associated with animal dross deposited in alitter box.

Another aspect of the compositions and methods described herein is toprovide a magnetically-attractable litter composition that facilitatesand reduces cleaning and maintenance of animal litter boxes and animalcages, particularly in areas surrounding the litter boxes and cages.

Still another aspect of the compositions and methods described herein isto provide a magnetically-attractable litter composition that overcomesthe cleaning disadvantages of prior art animal litter box absorbentcompositions, when the litter is scattered by the pet outside of thelitter box.

Another aspect of the compositions and methods described herein is toprovide a magnetically-attractable litter composition that, whenscattered outside of a confined area, e.g., a litter box, ismagnetically attracted to a defined magnetic collection area for easydisposal and/or reuse.

Still another aspect of the compositions and methods described herein isto provide a magnetic or electromagnetic clean-up method of removing thescattered magnetically-attractable litter particles from the magneticcollection area for re-use or discarding.

DETAILED DESCRIPTION

The litter box absorbent composition described herein comprises, in oneembodiment, a non-clumping absorbent particulate material combined withmagnetically-attractable metal-containing particles under pressureand/or high-shear, optionally with a suitable binder, preferably withouta binder other than water. The absorbent composition contains preferablyabout 50 to 98 weight % (more preferably about 80 to 97 weight %) of anon-clumping absorbent particulate material and preferably about 2 to 50weight % (more preferably about 3 to 20 weight %) ofmagnetically-attractable metal particles.

Non-Clumping Absorbent Particulate Material

The absorbent material suitable for the compositions herein is a fineparticulate material that sufficiently hydrates in the presence of waterbut does not clump to form a large agglomerated mass of soiled litter.As used herein, the term “absorbent” refers to the processes ofabsorption and/or adsorption. To achieve the full advantage of thecompositions and methods described herein, the absorbent material shouldhave a particle size such as that at least 25%, preferably at least 50%,more preferably at least 65% of the particles, by weight, pass through a50-mesh (U.S. Sieve Series) screen.

The non-clumping absorbent particulate materials useful in accordancewith the compositions and methods described herein include: calciumbentonite, talc, pyrophyllite, vermicullite, illite, phlogopite,muscovite clay, kaolinite clay, attapulgite (palygorskite), sepioliteclay, alganite, diatomite, tobermorite, marl, calcined clay, zeolite,silica, silica gel, sand, fullers earth, diatomaceous earth, cellulosicmaterial (wood including cedar, pine and etc, paper, cotton), corn cob,straw, rice husk, maize fiber alfalfa, wheat, peanut (and other nut)shells, grass, green tea leaves, absorbent polymers, calcium silicate,gypsum, synthetic gypsum, slate, pumice, building waste, or any mixtureof the above. The preferred non-clumping absorbent particulate materialsinclude non-swelling clays in general, and more preferably includenon-swelling clays such as calcium bentonite, kaolinite, attapulgite(palygorskite), and sepiolite.

Optionally, other additives, in amounts of about 1% to about 49%, can beadded to the non-clumping absorbent particulate material. Examples ofoptional additives include fragrances, color agents, anti-microbialagents, odor-control agents, odor-masking agents, bactericides, orcombinations thereof. However, any optionally-added ingredient cannot bepresent in an amount that materially and adversely affects the abilityof the litter particles to be attracted to a magnet and to absorb liquiddross products. Any optional ingredients may be blended into absorbentcomposition when mixed together using a high-shear mixer.

It should be noted that the animal dross absorbent compositionsdescribed herein can be used in litter boxes or in cages of animalsincluding, among others, household pets such as cats, dogs, gerbils,guinea pigs, mice and hamsters; other pets such as rabbits, ferrets andskunks; or laboratory animals such as monkeys, mice, rats, goats,horses, cows and sheep. The animal litter absorbent compositionsdescribed herein are especially useful for smaller animals, such ascats. Furthermore, the high-shear mixed or extruded compositionsdescribed herein are suitable for other uses in addition to absorbingurine, such as absorbing vomit or adsorbing waste liquids in appropriateareas of slaughter houses and meat packing plants.

Magnetically-Attractable Metal Particles

Magnetically-attractable metal particles suitable for the compositionsdescribed herein preferably contain iron, cobalt, and/or iron. Examplesof elements, alloys, compounds, and minerals that all fall within thedefinition of “metal” as used in this disclosure include: iron, nickel,cobalt, awaruite, wairauite, magnetite, taconite, maghemite, jacobsite,trevorite, magnesioferrite, pyrrhotite, greigite, and feroxyhyte.Preferably, the magnetically-attractable metal particles areiron-containing particles. Preferred iron-containing particles aretaconite and/or magnetite. To achieve the full advantage of thecompositions and methods described herein, the taconite particles shouldhave an iron content of at least about 20 weight %, preferably at leastabout 40 weight %, and more preferably at least about 50 weight %. Toachieve the full advantage of the compositions and methods describedherein, the magnetically-attractable metal-containing particles shouldpreferably have a particle size such that at least 25 weight % of theparticles, more preferably 50 weight %, even more preferably 65 weight%, are of size to pass through a 50-mesh screen (U.S. Sieve Series). Theconcentration of the magnetically-attractable metal particles in theabsorbent composition should be in the range of about 2% to about 50% byweight, preferably about 3% to about 20% by weight.

Binders (Optional)

The magnetically-attractable metal particles can be adhered to thenon-clumping absorbent particulate material with or without a suitablebinder. If a binder is used, the preferred binder is water, whichsurprisingly irreversibly adheres the metal-containing particles to theabsorbent particles via high-shear mixing. When an additional binder isused, the preferred binders are water-soluble adhesives including, butnot limited to, water-soluble polysaccharides, particularly awater-soluble cellulosic ether adhesive, such as carboxymethylcellulose, methyl cellulose, hydroxypropyl cellulose,hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, or mixturesthereof. A preferred amount of water-soluble polysaccharide (inparticular carboxymethyl cellulose) is about 0.025 to less than about0.1 weight %. Aqueous sodium silicate (available as product N® from PQCorporation, Valley Forge, Pa.) is also a preferred binder atconcentrations of up to about 5 weight %, more preferably from about 0.5to 2 weight %, and most preferably at about 1 weight %. Other usefulwater-soluble adhesives include alignates and starches, such as wheatpaste (a pregelatinized starch); gums, such as xanthan gum or guar gum;sodium or calcium lignosulfonate; glycerin; sucrose; lactose; dextrose;dextrin; water-soluble polymers, such as polyvinyl pyrrolidone,polyvinyl alcohol, or polyvinyl acetate, and those water-solublepolymers disclosed in this Assignee's U.S. Pat. No. 5,267,532, herebyincorporated by reference.

High-Shear Mixing

When mixed in a high-shear mixer, the magnetically-attractablemetal/absorbent composition provides increased individual particleresiliency (preferably at least about 50%, more preferably at leastabout 75%, and most preferably about 75 to 98%), and decreased mixtureinhomogeneity (preferably less than about 30%, more preferably less thanabout 20%, and most preferably less than about 10%) as compared to thesame material without high-shear mixing. See the attrition test methodsfor resiliency and inhomogeneity, infra. High-shear mixers arecharacterized by local velocity gradients and mixing patterns thatcompress absorbent and metal fines together, thereby binding them in astable, well-mixed aggregate of particles. It has been found thatwithout these aspects of high-shear mixing, the absorbent/metalcombination suffers from being dusty (because the fine absorbentparticles are not sufficiently agglomerated) and from a tendency of thefinal absorbent/metal particles to break apart during handling andstorage, thereby separating the absorbent from themagnetically-attractable metal. Examples of high-shear mixersappropriate for the present disclosure include pin mixers, pug mills,extruders, and counter-current mixers.

Generally, the water content of the absorbent/metal particle compositionduring mixing should be in the range of about 10–45 weight %, preferablyabout 15–40 weight %, and more preferably about 18–35 weight %, based onthe dry weight of the absorbent material, when the absorbent/metalparticle composition is mixed with a high-shear mixer. If the absorbentis too dry, it would be forced through, for example, the die openings ofan extruder or the exit of the pin-mixer, in a powdery form withoutsufficient adherence to the metal particles, resulting in insufficientagglomeration of absorbent and metal particles. If too wet when mixed,the absorbent/metal particle composition becomes very sticky and mayvery well clog the high-shear mixer.

Pin-Mixer

A pin mixer is a high-shear mixing device that is also called amicro-pelletizing device and is the preferred high-shear apparatus forcombining the absorbent and metal particles. It compresses the absorbentand metal particles together to form small particles that require nofurther grinding to provide a substantial percentage of permanentlycombined absorbent/metal particles that have the desired particle size.When removed from the pin-mixer, the particles are dried to less thanabout 15 weight % water, preferably to about 8–12 weight % water andthen screened to collect particles having a preferred size distribution,e.g., between 8 and 50 mesh, preferably 10 to 40 mesh, U.S. SieveSeries. The finer and larger particles may be recycled to the pin mixer.Preferably, at least about 60 weight %, and more preferably at leastabout 80 weight % of the particles exiting the pin mixer are within thedesired size distribution. The dried particles having the desired sizedistribution are tested for absorbency, attraction to a magnet,resiliency, and inhomogeneity.

The pin-mixers include an outer shell and a central, horizontal internalaxis that includes a number of impeller pins extending radiallyoutwardly that are closely spaced from an internal, cylindrical surfaceof the shell. An exemplary pin mixer is the model 8D32L mixer (availablefrom Mars Mineral, Mars, Pa.), which has an 8″ internal diameter, a 32″internal length, and about ½″-diameter impeller pins. In this mixer, theabsorbent and metal particles enter the pin mixer at an upper end(inlet) of the cylindrical shell and are whipped by the pins at animpeller tip speed of at least about 20 ft/sec (600 rpm), preferablyabout 25–75 ft/sec (700–2200 rpm), and more preferably at about 35–70ft/sec (1000–2000 rpm), as the absorbent and metal particles move towardan opposite end of the pin mixer toward a bottom outlet. Alternativegeometries and/or operating conditions for the pin mixer that increasethe residence time of the feed mixture may allow a reduction in thepreferable impeller tip speed that yields sufficiently bound aggregatesof absorbent and metal particles. As a fine spray of water is added withthe absorbent and metal particles at the inlet and distributedthroughout the absorbent and metal particles, high-shear mixing andmicro-agglomeration of the absorbent and metal particles occurs as aresult of the high-speed pins compressing and/or shearing the absorbentand metal particles together to provide homogeneous mixing of theabsorbent and metal particles and to form micro-pellets. The size of theabsorbent and metal particles added to the pin mixer, the percentage ofwater added, and the speed of rotation of the pins, can be varied toprovide micro-pellets that provide a high percentage of absorbent/metalparticles within the desired particle size distribution.

Pug Mill

Compression and/or shearing of the absorbent material and metal particlecomposition also can be conveniently carried out by using a pug mill,commonly used in the production of bricks and other ceramic materials.In general, conventional pug-mills include a tubular housing having oneend open for receiving materials and the other end closed with a flatwall including one or more die openings for extruding the materialtherethrough. Pug-mills useful in accordance with the compositions andmethods described herein may be further provided with a longitudinalaxis having one or more blades disposed radially thereon. In operation,the central axis is rotated to provide shearing forces to the materialwithin the pug-mill. The blades are inclined to a slight degree so that,as they turn, they force the absorbent material forward, toward the exitor extruding end. In this way, shear pressure forces are applied to theabsorbent material and metal particles within the pug-mill. The amountor intensity of shearing forces imparted by the extrusion may be variedby changing the feed rate of absorbent material and metal particles,blade size and/or blade angle, or the size of the extruding or dieopening. Also, the rotation speed of the central axis driving the mixingor auger blades and speed of the wiping blade may be varied to changeshear forces. The particular operating conditions and pug mill orextruder dimensions may be varied widely.

Extruder

Application of shear pressure forces also conveniently may be appliedutilizing a conventional auger extruder. Auger extruders are similar topug mills except that the central rotating axis has a single or doublescrew-type mixing blade which, when rotated in the appropriatedirection, mixes and conveys the absorbent material andmagnetically-attractable particles toward and then through one or moredie openings at the extruding end of the extruder housing. The absorbentmaterial and magnetically-attractable particles, when extruded, exitfrom the die opening in pellet form, and the pellets break off from anexit end of the die opening when the pellet increases in lengthsufficiently to provide enough weight that the pellet breaks at the dieopening exit. The pellets then are ground and sieved to the appropriateparticle size distribution. As with the pug-mill, the particulardimensions, including the extruder port or die hole size and shapeand/or wiper design and operating conditions may be varied widely toprovide varying degrees of shear forces to the absorbent material andmagnetically-attractable particles.

Counter-Current Mixer

High-shear mixing is also possible with a counter-current mixer. Acounter-current mixer is a batch mixer that generates large internalshear fields with multiple rotating surfaces. Exemplary counter-currentmixers include the Lancaster® K-Series mixers (available from LancasterProducts, Lebanon, Pa.). The outer wall of the circular mixing vesselrotates in one direction and an interior, high-speed mixing impellerrotates in the opposite direction, thereby increasing the local velocitygradients. The high-speed mixing impeller simultaneously meandersthroughout the entire mixer volume while secondary, low-speed scrapersprevent material from settling outside of the mixing zones. The specificgeometry and operating conditions of the mixer (e.g., rotation rate ofthe high-speed impeller, etc.) may be varied according the amounts andsize distributions of non-clumping absorbent particulate material andmagnetically-attractable particles added to the mixer as well as thedesired homogeneity, resiliency, and size distribution of the finalanimal litter composition. For example, with sufficient mixing time(e.g., in the range of about 5 minutes to about 1 hour), stableaggregates of absorbent and metal particles can be formed at impellertip speeds of at least about 2 ft/sec, and more preferably at impellertip speeds of at least about 5 ft/sec.

The batch nature of the counter-current mixer permits multistage mixing.For instance, the absorbent material and magnetically-attractableparticles may be blended in a first mixing stage. Once thoroughlyblended, a binder may be added in a second mixing stage that createsbound litter particles containing both absorbent material andmagnetically-attractable particles in the desired size distribution. Athird, post-processing mixing stage may then be used to add surfacecoatings such as, for example, fragrances, color agents, anti-microbialagents, odor-control agents, odor-masking agents, bactericides, orcombinations thereof.

Apparatus for the Collection of Magnetically-Attractable Animal Litter

It is desirable to have a convenient apparatus for the collection ofmagnetically-attractable animal litter according to the presentdisclosure. Magnetically-attractable animal litter outside the litterbox may result from accidental spills by the pet owner or fromindividual litter particles being tracked out of the litter box by thepet. A magnetic mat may be used to surround the litter box and collectlitter particles. An example of such a magnetic mat includes a flexibleferrite magnetic sheet (available under the name Flexmag™ from ArnoldMagnetic Technologies, Marietta, Ohio) preferably having a magneticenergy of about 0.6 to 1.6 MG·Oe, more preferably of about 0.8 to 1.4MG·Oe, and most preferably of about 1.0 to 1.2 MG·Oe. However, even if amagnetic mat is used to collect and contain litter particles, the petowner still needs a means for removing the particles from the magneticmat without resorting to vigorous scraping. Accordingly, FIGS. 1 and 2present devices able to remove errant litter particles in suchsituations.

FIG. 1 illustrates a perspective view of a magnetic sweeper 100 inaccordance with the present disclosure. The magnetic sweeper 100 has abase 140, the top surface of which has a hinge 130. One end of a stem120 is attached to the base 140 via the hinge 130 and the other end isfitted with a handle 110 for gripping. A magnetic plate 150 is attachedto the bottom of the base 140, and may be a permanent magnet. The bottomsurface 152 of the magnetic plate 150 may be used to collectfree-standing litter particles by brushing the magnetic sweeper 100across the littered area and attracting the magnetically-attractablelitter particles to the bottom surface 152. Additionally, the bottomsurface 152 of the magnetic plate 150 may be fitted with sliding pads(not shown), rollers (not shown), or brushes (not shown) to facilitatethe brushing movement.

In an alternate embodiment of the magnetic sweeper 100, the magneticplate 150 may be an electromagnet. In this case, batteries (not shown)to operate the electromagnet may be contained, for example, in thehandle 110, and a switch 112 on the stem 120 is used to selectivelypower on and power off the electromagnet. This embodiment has theadvantage that the electromagnet may be used to collect straymagnetically-attractable litter particles that have been captured by amagnetic mat surrounding the litter box, provided that the strength ofthe electromagnet is stronger than that of the litter-contacting surfaceof the magnetic mat. Additionally, this embodiment simplifies cleaningof the magnetic sweeper 100, because the particles collected by themagnetic plate 150 may be simply removed by powering off theelectromagnet.

FIG. 2 illustrates a perspective view of a hand-held electromagneticcollector 200 in accordance with the present disclosure. Theelectromagnetic collector 200 has a handle 210, the front of which isattached to stem 230. The front of the stem 230 has a hinge 240 that isattached an electromagnetic plate 250. Batteries (not shown) to operatethe electromagnetic plate 250 may be contained, for example, in thehandle 210, and a trigger 220 on the stem 230 is used to selectivelypower on and power off the electromagnetic plate 250. When powered on,the bottom surface 252 of the magnetic plate 250 may be used to collectlitter particles by brushing the electromagnetic collector 200 acrossthe littered area and attracting the magnetically-attractable litterparticles to the bottom surface 252. In this way, animal litterparticles may be removed from either magnetic or non-magnetic surfaces,provided that the strength of the electromagnet is stronger than that ofany magnetic surfaces.

In an alternate embodiment, the batteries (not shown) of theelectromagnetic collector 200 may be removed and replaced withvoltage/current regulators (not shown) in the handle 210. In this case,an external power cord (not shown) is attached to the handle 210 toprovide power to the electromagnetic plate 250.

Methods for Composition Characterization

[Particle Size Distribution] The size distribution of a population ofparticles, whether absorbent material fines individually,magnetically-attractable metal particles individually, or the aggregatecomposition of the present disclosure, is determined using standardsieves from the U.S. Sieve Series. A sample may also be classified usingtwo standard sieves, with the mesh numbers of the sieve representing theupper and lower particle sizes of the classification operation. The D50size of a population is the particle size above which 50 weight % of thepopulation is contained.

[Water Absorbency Test] The water absorbency test measures the abilityof a population of litter particles to absorb and retain liquid whenwetted with water. A filter-lined funnel is loaded with about 50 g ofthe litter sample to be tested. About 100 ml of distilled water ispoured over the litter sample at a rate of about 10 ml/min. Theunabsorbed water is collected in a graduated cylinder in order todetermine the weight of water absorbed by the litter sample. Theabsorbency is generally expressed in units of g/g (i.e., grams of waterabsorbed per gram of dry litter).

[Magnetic Cohesion Drop Test] The magnetic cohesion drop test measuresthe ability of individual litter particles to adhere to a magnetic matupon application of dynamic forces to the mat. A magnetic mat (3″×3″ mathaving a magnetic energy of about 1 MG·Oe) is loaded with about 200 g oflitter sample and then tipped vertically to remove any individual litterparticles not in sufficient contact with the mat to adhere to the mat.The particles removed from the mat in this way are not considered in thesubsequent calculations of the magnetic retention rate. Theparticle-laden mat is vertically dropped 1″ using a trap door onto a ¾″test sieve, dislodging some of the particles from the mat. The ratio ofthe weight of the particles on the mat post-drop to the weight of theparticles on the mat immediately pre-drop is averaged over fivesuccessive tests to determine the magnetic retention rate (generallyexpressed as a percent). The magnetic retention rate may be determinedafter consecutive drops to characterize the effect of particle size andloading on the litter sample's ability to adhere to the magnetic matupon application of dynamic forces.

[Attrition Test—Resiliency] The resiliency attrition test measures theability of a litter particle population to retain its particle sizecharacteristics when subjected to the simulated trauma ofpost-production litter handling that can result in particlefragmentation and fines formation. An initial 50 g litter sample havingparticle sizes between 12 and 40 mesh (i.e., between about 425 μm and1.68 mm) is fragmented in the pan of a rotary test sieve shakercontaining ten (10) ⅝″-diameter ball bearings for 5 minutes. The rotarytest sieve shaker used simultaneously swirls (at about 280 rpm) and taps(at a frequency of about 150 min⁻¹) the sample particles, and isavailable under the name Ro-Tap® 8″ RX-29, Model B (available from W.S.Tyler, Mentor, Ohio). After fragmentation of the litter particles by theball bearings, the litter sample is reanalyzed with the rotary testsieve shaker by rotating, without ball bearings, the fragmentedparticles for another 5 minutes in a 40-mesh sieve. After this step, theweight fraction of litter particles retained on the 40-mesh sievepost-fragmentation is reported as the resiliency of the sample(generally expressed as a percent).

[Attrition Test—Inhomogeneity] The inhomogeneity attrition test measuresthe ability of a litter particle population to retain its degree ofattraction to a magnetic surface when subjected to the simulated traumaof post-production litter handling that can result in particlefragmentation and fines formation. The particle size distribution of a 5g litter sample is determined and then the litter sample is evenlyspread across a 2″-diameter circular area on a magnetic mat (3″×3″ mathaving a magnetic energy of about 1 MG·Oe). The mat is then rotated to avertical position, thereby allowing any particles insufficiently adheredto the mat surface to fall, and the fraction of litter sample retainedis calculated gravimetrically. The entire 5 g litter sample is thenrecovered (i.e., the particles remaining on the mat are scraped from themat and recombined with the particles that fell from the mat) andhand-crushed on a hard surface until the D50 of the litter sample isreduced by at least about ⅓ (as verified by measurement of the particlesize distribution). The crushed sample is then evenly spread across the2″-diameter circular area of the magnetic mat, the mat is rotated to avertical position, and the fraction of litter sample retained iscalculated gravimetrically. The inhomogeneity (generally expressed as apercent) of the litter sample is calculated as the difference betweenthe average fraction retained on the mat of the three median values fromfive successive tests pre-crushing and the same average post-crushing.

PRODUCT EXAMPLES Example 1 (Sample L-9)

368.0 g of attapulgite (FLORIGEL® H-Y from ITC, Inc. Hunt Valley, Md.)were mixed with 32.0 g of taconite fines using a kitchen aid mixer forone minute. 180.0 g of water were added to the attapulgite-taconitemixture and mixed for another three minutes. The mixture was oven-driedat 110° C. to a moisture content of about 8% to 12%. Dried particleswith sizes between 8 and 40 mesh were collected and further tested fortheir performance as illustrated in Tables 1, 2, and 3.

Example 2 (Sample L-10)

368.0 g of corn cob powder (from Mass Finishing, Inc. Howard Lake,Minn.) were mixed with 32.0 g of taconite fines using a kitchen aidmixer for one minute. 100.0 g of water were added to the corncob-taconite mixture and mixed for another three minutes. The mixturewas air-dried to a moisture content of about 1% to 5% so that thematerial was free-flowing. Dried particles with sizes between 8 and 40mesh were collected and further tested for their performance asillustrated in Tables 1, 2, and 3.

Example 3 (Sample L-11A)

368.0 g of gypsum powder (calcium sulfate dehydrate from SpectrumLaboratory Products Inc., Gardena, Calif.) were mixed with 32.0 g oftaconite fines using a kitchen aid mixer for one minute. 18.4 g ofsodium silicate solution (37.11 weight % aqueous sodium silicate,product N® from PQ Corporation, Valley Forge, Pa.) and 72.0 g of waterwere added to the gypsum-taconite mixture and mixed for another threeminutes. The mixture was oven-dried at 110° C. to a moisture content ofabout 10% to 15%. Dried particles with sizes between 8 and 40 mesh werecollected and further tested for their performance as illustrated inTables 1, 2, and 3.

Comparative Example (Sample L-11)

368.0 g of gypsum powder (calcium sulfate dehydrate from SpectrumLaboratory Products Inc., Gardena, Calif.) were mixed with 32.0 g oftaconite fines using a kitchen aid mixer for one minute. 72.0 g of waterwere added to the gypsum-taconite mixture and mixed for another threeminutes. The mixture was oven-dried at 110° C. to a moisture content ofabout 10% to 15%. Dried particles with sizes between 8 and 40 mesh werecollected and further tested for their performance as illustrated inTables 1, 2, and 3.

Example 4 (Sample L-12)

368.0 g of attapulgite (FLORIGEL® H-Y from ITC, Inc. Hunt Valley, Md.)were mixed with 32.0 g of taconite fines using a kitchen aid mixer forone minute. 280.0 g of water were added to the attapulgite-taconitemixture and mixed for another three minutes. The mixture was extrudedonce using a laboratory scale extruder with a die-plate. The extrudateswere oven-dried at 110° C. to a moisture content of about 8% to 12%. Thedried extrudates were ground and particles with sizes between 8 and 40mesh were collected and further tested for their performance asillustrated in Tables 1, 2, and 3.

TABLE 1 Composition and Process Summary Sample Composition AdditiveMixing Method L-9 Attapulgite/Taconite None Low-shear agglomeration(92:8 weight basis) L-10 Corn Cob/Taconite None Low-shear agglomeration(92:8 weight basis) L-11 Gypsum/Taconite None Low-shear agglomeration(92:8 weight basis) L-11A Gypsum/Taconite Sodium Silicate Low-shearagglomeration (92:8 weight basis) L-12 Attapulgite/Taconite NoneHigh-shear extrusion (92:8 weight basis)

TABLE 2 Magnetically-attractable Litter Magnetic Effect MagneticRetention Rate Sample After 1^(st) Drop After 2^(nd) Drop After 3^(rd)Drop L-9 26.0% 76.1% 64.4% L-10 29.9% 57.1% 73.6% L-11 33.1% 71.8% 80.6%L-11A 37.1% 74.7% 84.6% L-12 32.2% 71.3% 74.4%

TABLE 3 Magnetically-attractable Litter Performance Properties SampleBulk Density (lb/ft³) Water Absorbency (g/g) Resiliency (%) L-9 37.11.97 48.2 L-10 47.0 1.40 68.3 L-11 49.4 0.82 0.1 L-11A 49.7 0.91 52.7L-12 36.6 1.86 65.6

Although the foregoing text is a detailed description of numerousdifferent embodiments of an animal litter composition, the detaileddescription is to be construed as exemplary only and does not describeevery possible embodiment of an animal litter composition in accordancewith the disclosure.

1. A particulate non-clumping animal litter composition, comprising: (a)about 50 to 98 weight % of a non-clumping absorbent particulatematerial; and, (b) about 2 to 50 weight % of magnetically-attractablemetal particles; wherein: (i) the non-clumping absorbent particulatematerial and magnetically-attractable metal particles are boundtogether; and, (ii) substantially all particles of the animal littercomposition are attracted to a magnetic surface.
 2. The animal littercomposition of claim 1, wherein the resiliency of the animal littercomposition is at least about 40%, the resiliency being determined bymeasuring the weight fraction of animal litter particles initiallylarger than 40 mesh that are retained on a 40-mesh sieve after beingfragmented by swirling at a rate of about 280 rpm and tapping at afrequency of about 150 min⁻¹ for 5 minutes in the pan of a rotary testsieve shaker containing ten ⅝″-diameter ball bearings.
 3. The animallitter composition of claim 2, wherein the resiliency of the animallitter composition is at least about 45%.
 4. The animal littercomposition of claim 3, wherein the resiliency of the animal littercomposition is about 50 to 98%.
 5. The animal litter composition ofclaim 1, comprising about 80 to 97 weight % of the non-clumpingabsorbent particulate material and 3 to 20 weight % ofmagnetically-attractable metal particles.
 6. The animal littercomposition of claim 1, wherein the non-clumping absorbent particulatematerial comprises calcium bentonite, talc, pyrophyllite, vermicullite,illite, phlogopite, muscovite clay, kaolinite clay, attapulgite,sepiolite clay, alganite, diatomite, tobermorite, marl, calcined clay,zeolite, silica, silica gel, sand, fullers earth, diatomaceous earth,cellulosic material, corn cob, straw, rice husk, maize fiber alfalfa,wheat, nut shells, grass, green tea leaves, absorbent polymers, calciumsilicate, gypsum, synthetic gypsum, slate, pumice, building waste, ormixtures thereof.
 7. The animal litter composition of claim 1, whereinthe non-clumping absorbent particulate material comprises a non-swellingclay.
 8. The animal litter composition of claim 7, wherein thenon-swelling clay is selected from the group consisting essentially of:calcium bentonite, kaolinite, attapulgite, and sepiolite.
 9. The animallitter composition of claim 1, wherein non-clumping absorbentparticulate material has a particle size distribution such that at least25 weight % of the particles pass a 50-mesh sieve.
 10. The animal littercomposition of claim 1, wherein the magnetically-attractable metalparticles comprise iron, nickel, cobalt, or mixtures thereof.
 11. Theanimal litter composition of claim 1, wherein themagnetically-attractable metal particles have a particle sizedistribution such that at least 25 weight % of the particles pass a50-mesh sieve.
 12. The animal litter composition of claim 1, wherein themagnetically-attractable metal particles comprise magnetite, taconite,or mixtures thereof.
 13. The animal litter composition of claim 1,wherein the magnetically-attractable metal particles comprise taconitehaving an iron content of at least 25 weight %.
 14. The animal littercomposition of claim 1, wherein the particles of the animal littercomposition have particle sizes between 8 and 50 mesh.
 15. The animallitter composition of claim 14, wherein the particles of the animallitter composition have particle sizes between 10 and 40 mesh.
 16. Theanimal litter composition of claim 1, further comprising an additiveselected from the group consisting essentially of: carboxymethylcellulose, methyl cellulose, hydroxypropyl cellulose,hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, sodiumsilicate, starch, dextrin, xanthan gum, guar gum, lignin, sodium orcalcium lignosulfonate and their derivatives, sucrose, lactose, anddextrose.
 17. The animal litter composition of claim 1, furthercomprising an additive selected from the group consisting essentiallyof: carboxymethyl cellulose, sodium silicate, xanthan gum, and guar gum.18. The animal litter composition of claim 1, further comprising anadditive selected from the group consisting essentially of: a fragrance,a color agent, an anti-microbial agent, an odor-control agent, anodor-masking agent, and a bactericide.
 19. The animal litter compositionof claim 1, further comprising a surface coating selected from the groupconsisting essentially of: a fragrance, a color agent, an anti-microbialagent, an odor-control agent, an odor-masking agent, and a bactericide.20. A particulate non-clumping animal litter composition, comprising:(a) about 50 to 98 weight % of a non-clumping absorbent particulatematerial; and, (b) about 2 to 50 weight % of magnetically-attractablemetal particles; wherein: (i) the non-clumping absorbent particulatematerial and magnetically-attractable metal particles are boundtogether; and, (ii) the inhomogeneity of the animal litter compositionis not more than about 30%, wherein the inhomogeneity is determined bymeasuring the reduction in weight fraction of animal litter particlesadhering to a vertical magnetic surface after being crushed such thatthe D50 of the animal litter particles after crushing is at least about⅓ less than the D50 of the animal litter particles before crushing. 21.The animal litter composition of claim 20, wherein the inhomogeneity ofthe animal litter composition is not more than about 20%.
 22. The animallitter composition of claim 21, wherein the inhomogeneity of the animallitter composition is not more than about 10%.
 23. A method ofmanufacturing a magnetically-attractable particulate non-clumping animallitter, comprising: mixing about 50 to about 98 weight % of anon-clumping absorbent particulate material together with about 2 toabout 50 weight % of magnetically-attractable metal particles; whereinthe mixing is accomplished with mixer that imparts sufficient shear tothe absorbent and metal particles such that: (i) the non-clumpingabsorbent particulate material and magnetically-attractable metalparticles are bound together in stable, non-dusty aggregates; and, (ii)substantially all particles of the animal litter composition areattracted to a magnetic surface.
 24. The method of claim 23, wherein theresiliency of the animal litter composition is at least about 50%, theresiliency being determined by measuring the weight fraction of animallitter particles initially larger than 40 mesh that are retained on a40-mesh sieve after being fragmented by swirling at a rate of about 280rpm and tapping at a frequency of about 150 min⁻¹ for 5 minutes in thepan of a rotary test sieve shaker containing ten ⅝″-diameter ballbearings.
 25. The method of claim 23, wherein the mixer is selected fromthe group consisting essentially of: a pin mixer, a pug mill, anextruder, or a counter-current mixer.
 26. The method of claim 23,wherein the mixer comprises a rotating impeller having a tip, whereinthe impeller tip speed is about 2 to 85 ft/sec.
 27. The method of claim26, wherein the mixer comprises a rotating impeller having a tip,wherein the impeller tip speed is about 5 to 75 ft/sec.
 28. The methodof claim 27, wherein the mixer comprises a rotating impeller having atip, wherein the impeller tip speed is about 20 to 70 ft/sec.
 29. Themethod of claim 28, wherein the mixer comprises a rotating impellerhaving a tip, wherein the impeller tip speed is about 35 to 65 ft/sec.30. A method of manufacturing a magnetically-attractable particulatenon-clumping animal litter having a particular final particle sizedistribution, comprising mixing a non-clumping absorbent particulatematerial together with magnetically-attractable metal particles,wherein: (i) the non-clumping absorbent particulate material has a D50less than the D50 of the final particle size distribution of themagnetically-attractable particulate clumping animal litter; and, (ii)the mixing is accomplished with sufficient shear to adhere thenon-clumping absorbent particulate material and themagnetically-attractable metal particles and to provide water-absorbentmagnetically-attractable particulate clumping animal litter particleshaving the particular final particle size distribution without grindingor otherwise subdividing the adhered absorbent and metal particles. 31.The method of claim 30, wherein the D50 of the non-clumping absorbentparticulate material is less than about 300 μm.
 32. The method of claim31, wherein the D50 of the non-clumping absorbent particulate materialis less than about 200 μm.
 33. The method of claim 30, wherein at leastabout 60 weight % of the magnetically-attractable particulate clumpinganimal litter particles generated by the mixing step have sizes between8 and 50 mesh.
 34. The method of claim 33, wherein about 70 to 99 weight% of the magnetically-attractable particulate clumping animal litterparticles generated by the mixing step have sizes between 8 and 50 mesh.35. The method of claim 34, wherein about 80 to 95 weight % of themagnetically-attractable particulate clumping animal litter particlesgenerated by the mixing step have sizes between 8 and 50 mesh.
 36. Themethod of claim 30, wherein about 75 to 95 weight % of themagnetically-attractable particulate clumping animal litter particlesgenerated by the mixing step have sizes between 10 and 40 mesh.
 37. Aparticulate clumping animal litter composition, comprising: (a) about 85to 95 weight % of non-swelling clay particles having a particle sizedistribution such that at least 50 weight % of the particles pass a50-mesh sieve; and, (b) about 5 to 15 weight % ofmagnetically-attractable metal particles having a particle sizedistribution such that at least 50 weight % of the particles pass a50-mesh sieve, the magnetically-attractable metal particles comprisingmagnetite, taconite, or mixtures thereof; wherein: (i) the attapulgiteparticles and magnetically-attractable metal particles are boundtogether; (ii) the particles of the animal litter composition haveparticle sizes between 8 and 50 mesh; (iii) substantially all particlesof the animal litter composition are attracted to a magnetic surface;and, (iv) the resiliency of the animal litter composition is at leastabout 50%, the resiliency being determined by measuring the weightfraction of animal litter particles initially larger than 40 mesh thatare retained on a 40-mesh sieve after being fragmented in the pan of arotary test sieve shaker containing ten ⅝″-diameter ball bearings for 5minutes.
 38. The animal litter composition claim 37, wherein theinhomogeneity of the animal litter composition is not more than about20%, wherein the inhomogeneity is determined by measuring the reductionin weight fraction of animal litter particles adhering to a verticalmagnetic surface after being crushed such that the D50 of the animallitter particles after crushing is at least about ⅓ less than the D50 ofthe animal litter particles before crushing.
 39. The animal littercomposition of claim 37, wherein the non-swelling clay is selected fromthe group consisting essentially of: calcium bentonite, kaolinite,attapulgite, and sepiolite.
 40. A method for the collection ofmagnetically-attractable animal litter, comprising the step of brushinga collection device over an area contaminated with individualmagnetically-attractable animal litter particles, the collection devicecomprising a magnetic plate, a stem, and a handle.
 41. The method ofclaim 40, the collection device further comprising a source of energy,wherein the magnetic plate is an electromagnet.